In short-channel devices this is no longer true: The drain is close enough to gate the channel, and so a high drain voltage can open the bottleneck and turn on the transistor prematurely. The origin of the threshold decrease the mos transistor yannis tsividis pdf be understood as a consequence of charge neutrality: the Yau charge-sharing model. As a result, the charge present on the gate retains charge balance by attracting more carriers into the channel, an effect equivalent to lowering the threshold voltage of the device. In effect, the channel becomes more attractive for electrons.
In other words, the potential energy barrier for electrons in the channel is lowered. Hence the term “barrier lowering” is used to describe these phenomena. Unfortunately, it is not easy to come up with accurate analytical results using the barrier lowering concept. However, at shorter lengths the slope of the current vs.
At extremely short lengths, the gate entirely fails to turn the device off. These effects cannot be modeled as a threshold adjustment. DIBL also affects the current vs. Vtlin is the threshold voltage measured at a very low drain voltage, typically 0. The minus in the front of the formula ensures a positive DIBL value.
This page was last edited on 24 October 2016, at 07:25. I don’t have a pun to go with that one. Did you click the AcIS link? 65 years of computing at Columbia University. Columbia University School of Mines, Vol.
Computing Laboratory at Columbia University in the 1940s and 50s. Columbia University, and his continuing adventures. Who am I and why did I write this? I was there for most of it.